Mexico will sue the United States in response to a suspected terror attack that killed three of its citizens and injured nine more. 

Its foreign minister, Marcelo Ebrard, announced the actionb in a video posted to Twitter on Sunday morning, reported The Arizona Republic, an American sister paper of The Herald.

Mr Ebrard expressed his "indignation" for Saturday's shooting, which left 20 people dead and 26 injured and which is being treated as terrorism by US federal authorities.

READ MORE: El Paso mass shootings to be treated as terror attack

The Mexican minister referred to the mass shooting as a "barbarous" act, and said the Mexican government would be taking action to protect its citizens living in the United States.

"The president of the Republic has instructed me so that this posture and indignation from Mexico is translated, first in protecting affected families, and then in legal actions, efficient and prompt, quick and convincing so that Mexico can demand the conditions to protect to the Mexican-American community and Mexicans in the United States," he said.

 

Mr Ebrard offered no additional details in the short video. But he said that a formal announcement of the legal actions the nation will take would come later in the day.

"What happened is inadmissible and today (Sunday), at 4 p.m., we will announce the first judicial actions that the Mexican government will take in accordance to international law," he added.

READ MORE: Mum gave her life to protect baby son in El Paso terror attack

On Saturday evening, Mexican President Andres Manuel Lopez Obrador also tweeted a video offering his condolences, saying that at least three Mexican nationals had been killed.

Ebrard also sent out information via Twitter on Saturday saying they were Mr working with the Mexican Consulate in El Paso to identify and offer assistance to Mexican nationals injured in the shooting.

Among those injured, he pointed out to a family of three, a couple from Chihuahua and their 10-year-old daughter, who were hospitalized with bullet injuries.